A known method of measuring amount of ink remaining in an inkjet printer and notifying the user of the timing for ink replacement is a method of recording total amount of ink used from the start of use of each ink tank and prompting the user to effect ink replacement when the total amount of ink used approaches total amount of ink loaded into each ink tank beforehand. Another method involves, conversely, subtracting amount of ink used from an initial value that is based upon the total amount of ink loaded in an ink tank beforehand, and prompting the user to effect ink replacement when the value of the difference falls below a fixed value. Since these methods do not require sensors or the like for directly measuring amount of remaining ink, they are often used in ink-jet printers of comparatively inexpensive type. In order to monitor remaining amount of ink correctly with these methods, it is required that a counter for measuring amount of ink used be initialized correctly when the user performs ink replacement.
A known method of initializing the counter for measuring amount of ink used is a method of monitoring the ink-tank exchange operation at the printer and, if the exchange has been performed, regarding this as indicating that the ink tank has been exchanged for a new tank and initializing the counter automatically (see the specification of Japanese Patent Application Laid-Open No. 09-30006).
Another method involves initializing the counter for measuring amount of ink used by having the user perform a predetermined counter initializing operation after ink replacement is carried out (see the specification of Japanese Patent Application Laid-Open No. 8-224891). To facilitate operation, there are cases where a GUI (Graphical User Interface) for initializing the counter is presented on the screen of a host computer connected to the printer, a command for initializing amount of ink used is transferred to the printer by clicking a button on the GUI, and the counter is initialized in response to this command.
The above-described methods have certain problems. With the method of initializing the counter for measuring amount of ink used automatically upon sensing the ink-tank replacement operation, the counter is initialized automatically in a case where replacement has been sensed. As a consequence, the counter is initialized even in a case where the actual remaining amount of ink has not changed, as when an ink tank still in use is temporarily removed and then re-inserted. This means that the counter will not correctly reflect the amount of ink remaining in this ink tank. In order to avoid this problem, the ink tank may be provided with a microchip for identifying the particular ink tank. However, this leads to higher cost.
Further, with the method in which the user performs the operation for initializing the counter for amount of ink used after the ink replacement operation, the counter will not correctly reflect the amount of ink used in a case where the user has not performed the counter initializing operation.